Methods for extracting and retrieving the uranium present in an aqueous solution including phosphoric acid

Abstract

A method for extracting uranium (VI) from an aqueous solution including phosphoric acid, which includes placing the aqueous solution 5 in contact with an organic material, followed by separating the aqueous solution and the organic material. The organic material includes a solid polymer substrate impregnated with a compound having the following general formula (I): The invention also relates to a method for retrieving uranium (VI) from an aqueous solution including phosphoric acid.

What is claimed is: 
     
         1 . Method for extracting uranium(VI) from an aqueous solution S comprising phosphoric acid, this method including placing the aqueous solution S in contact with an organic material, followed by separation of the aqueous solution and the organic material, characterized in that the organic material comprises a solid polymeric substrate impregnated with a compound meeting following general formula: 
       
         
           
           
               
               
           
         
         where:
 m is an integer of 0, 1 or 2; 
 R 1  and R 2 , the same or different, are a linear or branched, saturated or unsaturated hydrocarbon group having 6 to 12 carbon atoms; 
 R 3  is:
 a hydrogen atom; 
 a linear or branched, saturated or unsaturated hydrocarbon group having 1 to 12 carbon atoms and optionally one or more heteroatoms; 
 a saturated or unsaturated hydrocarbon group comprising one or more rings of 3 to 8 carbon atoms, the ring(s) optionally comprising one or more heteroatoms; or 
 an aryl group comprising one or more rings, the ring(s) optionally comprising one or more heteroatoms; 
 
 or else R 2  and R 3  together form a group —(CH 2 ) n — where n is an integer ranging from 1 to 4; 
 R 4  is:
 a linear or branched, saturated or unsaturated hydrocarbon group having 2 to 8 carbon atoms; 
 a saturated or unsaturated hydrocarbon group comprising one or more rings, the ring(s) optionally comprising one or more heteroatoms; or 
 an aromatic group comprising one or more rings, the ring(s) optionally comprising one or more heteroatoms; and 
 
 R 5  is a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group having 1 to 12 carbon atoms. 
 
       
     
     
         2 . The extraction method according to  claim 1 , wherein the compound meets the following particular formula (I-a): 
       
         
           
           
               
               
           
         
         where:
 R 1  and R 2  are an alkyl group having 8 to 10 carbon atoms; 
 one from among R 3  and R 5  is a hydrogen atom and the other from among R 3  and R 5  is an alkyl group having 4 to 10 carbon atoms; and 
 R 4  is an alkyl group having 4 to 6 carbon atoms. 
 
       
     
     
         3 . The extraction method according to  claim 1 , wherein the compound is selected from among:
 ethyl 1-(N,N-diethylhexylcarbamoyl)ethylphosphonate, meeting the particular formula (I-a) where R 1  and R 2  are both a 2-ethylhexyl group, R 4  is an ethyl group, one from among R 3  and R 5  is a hydrogen atom whilst the other from among R 3  and R 5  is a methyl group;   ethyl 1-(N,N-diethylhexylcarbamoyl)nonylphosphonate, meeting the particular formula (I-a) where R 1  and R 2  are both a 2-ethylhexyl group, R 4  is an ethyl group, one from among R 3  and R 5  is a hydrogen atom whilst the other from among R 3  and R 5  is an n-octyl group;   butyl 1-(N,N-diethylhexylcarbamoyl)nonylphosphonate, meeting the particular formula (I-a) where R 1  and R 2  are both a 2-ethylhexyl group, R 4  is an n-butyl group, one from among R 3  and R 5  is a hydrogen atom whilst the other from among R 3  and R 5  is an n-octyl group;   butyl 1-(N,N-dioctylcarbamoyl)nonylphosphonate, meeting the particular formula (I-a) where R 1  and R 2  are both an n-octyl group, R 4  is an n-butyl group, one from among R 3  and R 5  is a hydrogen atom whilst the other from among R 3  and R 5  is an n-octyl group; and   isopropyl 1-(N,N-diethylhexylcarbamoyl)nonylphosphonate, denoted DEHCNPIP, meeting the particular formula (I-a) above where R 1  and R 2  are both a 2-ethylhexyl group, R 4  is an isopropyl group, one from among R 3  and R 5  is a hydrogen atom whilst the other from among R 3  and R 5  is an n-octyl group,   the compound preferably being butyl 1-(N,N-diethylhexylcarbamoyl)nonylphosphonate.   
     
     
         4 . The extraction method according to  claim 1 , wherein the solid polymeric substrate is formed of a polymer comprising at least one repeat unit selected from among an olefin unit, benzene unit, acrylic ester unit and mixtures of these units, this polymer advantageously being a divinylbenzene/styrene copolymer or an acrylic ester polymer. 
     
     
         5 . The extraction method according to  claim 1 , wherein the solid polymeric substrate has a specific surface area, determined by the BET method, of between 300 m 2 /g and 1000 m 2 /g. 
     
     
         6 . The extraction method according to  claim 1 , wherein the solid polymeric substrate is in the form of beads of which at least 90% by number advantageously have a mean bead size d 90  of between 200 μm and 900 μm. 
     
     
         7 . The extraction method according to  claim 1 , wherein the organic material comprises at least 2.5 wt. %, advantageously from 10 wt. % to 70 wt. % and, preferably, from 20 wt. % to 60 wt. % of compound. 
     
     
         8 . The extraction method according to  claim 1 , wherein the contacting of the aqueous solution S with the solid organic material comprises at least one circulation of a mobile phase formed by the aqueous solution S, on a stationary phase formed by the organic material. 
     
     
         9 . Method for recovering uranium(VI) from an aqueous solution S comprising phosphoric acid, said method comprises:
 (a) extracting uranium(VI) from the aqueous solution S with an extraction method according to  claim 1 ; and   (b) placing the organic material obtained after step (a) in contact with a basic aqueous solution, followed by separation of the organic material and the basic aqueous solution after which uranium(VI) is recovered in the basic aqueous solution.   
     
     
         10 . The recovery method according to  claim 9 , wherein the placing in contact of the organic material obtained after step (a) with the basic aqueous solution comprises the eluting, with a mobile phase formed by the basic aqueous solution, of a stationary phase formed by the organic material. 
     
     
         11 . The recovery method according to  claim 9 , wherein the basic aqueous solution has a pH of 8 or higher, advantageously of between 8.5 and 12 and, preferably, of between 9 and 11. 
     
     
         12 . The recovery method according to  claim 9 , wherein the basic aqueous solution is an aqueous solution of an alkaline metal salt or ammonium salt, the salt being advantageously selected from among a carbonate and the metal being advantageously selected from among sodium and potassium. 
     
     
         13 . The recovery method according to  claim 9 , further comprising regeneration of the organic material, the regeneration comprising, after step (b):
 (c) placing the organic material obtained after step (b) in contact with an acid aqueous solution, followed by separation of the organic material and the acid aqueous solution after which the organic material is regenerated.   
     
     
         14 . The recovery method according to  claim 14 , further comprising, between steps (b) and (c):
 (b′) washing with water of the organic material separated at step (b).   
     
     
         15 . The recovery method according to  claim 13 , wherein the contacting of the organic material separated at step (b), and optionally washed at step (b′), with the acid aqueous solution comprises at least one washing with a mobile phase formed by the acid aqueous solution, on a stationary phase formed by the organic material. 
     
     
         16 . The recovery method according to  claim 13 , wherein the aqueous acid solution has a concentration of if ions of 20 mol/L or less, advantageously between 0.1 mol/L and 10 mol/L and, preferably, between 1 mol/L and 7 mol/L. 
     
     
         17 . The recovery method according to  claim 13 , wherein the aqueous acid solution comprises at least one inorganic acid selected from the group formed by sulfuric acid, nitric acid, phosphoric acid and hydrochloric acid, this inorganic acid being advantageously sulfuric acid. 
     
     
         18 . The extraction method according to  claim 1 , wherein the aqueous solution S comprises at least 0.1 mol/L, advantageously from 1 mol/L to 10 mol/L, preferably from 2 mol/L to 9 mol/L and, more preferably, from 3 mol/L to 7 mol/L of phosphoric acid. 
     
     
         19 . The extraction or recovery method according to  claim 18 , characterized in that the aqueous solution S is a solution resulting from attack of a natural phosphate by sulfuric acid. 
     
     
         20 . The recovery method according to  claim 9 , wherein the aqueous solution S comprises at least 0.1 mol/L, advantageously from 1 mol/L to 10 mol/L, preferably from 2 mol/L to 9 mol/L and, more preferably, from 3 mol/L to 7 mol/L of phosphoric acid. 
     
     
         21 . The extraction or recovery method according to  claim 20 , characterized in that the aqueous solution S is a solution resulting from attack of a natural phosphate by sulfuric acid.